Mobile phones are often used in areas that include high background noise. This noise is often of such a level that intelligibility of the spoken communication from the mobile phone speaker is greatly degraded. In many cases, some communication is lost or at least partly lost because a high ambient noise level masks or distorts a caller's voice, as it is heard by the listener.
Attempts to minimize loss of intelligibility in the presence of high background noise have involved use of equalizers, clipping circuits, or simply increasing the volume of the mobile phone. Equalizers and clipping circuits can themselves increase background noise, and thus fail to solve the problem. Increasing the overall level of sound or speaker volume of the mobile phone often does not significantly improve intelligibility and can cause other problems such as feedback and listener discomfort.